Patent GB-1166021-A (GB)
Title: Electrical Apparatus for Operating Doors
IPC: H02P7/00
Filed: 1968-01-25
Abstract: 1,166,021. Up and over doors; obstruction safety device. OVERHEAD DOOR CORP. 25 Jan., 1968 [7 March, 1967], No. 4020/68. Heading E2M. [Also in Divisions H1 and H2] A door, having a substantially vertical closed position and a substantially horizontal open position, and movable by rollers in guide side rails, is operated by a remotecontrolled reversible motor 34 associated with limit switches 67, 68, having actuators 71, 72 engageable by nuts 45, 46, on a motor-driven shaft 24. Change-over relay 73 energised from transformer 74 through push-button switch 76, which is shunted by switches 79, 84. The normally open safety switch 79 has an actuator 82 which responds to close the switch if the door strikes an obstruction as it is moving upwardly or downwardly except when the door is near a threshold. The relay 73 is adapted to reverse the motor. A switch 84 has an actuating arm 86 engaged by nut 46 to open the switch just before the door reaches its lowest position, as determined by opening of the limit switch 68. The limit switch 68 is opened but the door is not reversed if an obstruction is engaged by the door when it approaches the threshold but before the limit switch would be normally opened by the nut 46. A rocker arm 87 and trigger 88 are provided for this purpose. A lamp 78 is energised while the door is being opened. A pair of slide rails 18, 19 supports a shuttle coupled by an arm to the door, a sprocket 37 engaging a chain secured to the shuttle which is also joined to a cable 39 extending around pulley 42. A bar 48 prevents rotation of the nuts 45, 46. The chain engages an idler sprocket (53), supported on a safety switch actuating member (56) which is moved against spring (62) when the door meets an obstruction Fig. 3 (not shown). The rocker arm 87 is pivoted at a point between the switches 67, 68 and has an integral element 93 so that the leftward end of the arm is moved upwardly by the actuator 71 when switch 67 is opened by nut 45. A further element on the arm 87 causes the actuator 72 to open the switch 68 when the rightward end of the arm is moved upwardly by a spring 96. The pivoted trigger 88 is engageable by a tab 103 on the member (56) and is spring-urged toward the rail 10. The trigger is engaged by the arm 87 when the member (56) is adjacent the rail 18. However, movement away from the rail due to the door meeting an obstruction, disengages the trigger from the arm 87 to open the limit switch 68. The switch 84 is opened by nut 46 when the door is a short distance above the ground, closure of the safety switch 79 by the member (56) having no effect. However, the switch 68 is then opened if the trigger 88 is pivoted. If the trigger is operated while the door is moving within the small range adjacent the fully-closed position, operation of the pushbutton 76 cannot cause the door to close until the door reaches the fully-open position and arm 87 is recocked by nut 45, whereby trigger 88 is spring-returned into its cocked position. When the door is closed, actuation of pushbutton 76 energises relay 73 to complete the motor circuit through limit switch 67, an overload switch operating if the door is obstructed during a short range of upward movement. After this height has been exceeded, the switch 84 being closed, the door will be reversed back to the closed position if switch 79 is closed, unless the trigger 88 has opened switch 68, whereupon the motor is stopped but not reversed. Reactuation of the push-button continues opening movement of the door until limit switch 67 is operated and switch 68 permitted to close. If, while the door is being closed, it is obstructed before it approaches the threshold, the motor is reversed and the door is re-opened.